The 27-year old Czech defender spent last season on loan at Vicarage Road but is now back permanently and looking to go one better than the Championship playoff final of last season.
"Last season was the best in my career, even if we did eventually miss out on winning a place in the Premier League," he told chovanecsport.cz.
"We were playing excellent football. We have fantastic fans and I am glad that I can continue at this club.
"It is also ideal for my family. We have settled down in London and love it there. Our son goes to pre-school and my girlfriend wants to study there."